Chroma Keying is a process to create a transparent background from a specific existing background color. The most popular background colors used are green and blue. This Technic is used in for both photo & video. In video production and live broadcast this is very popular and used widely all over the world for many purposes like reading the weather and now most popular in conjunction with Virtual Sets. The idea is to place the subject usually a person in front of the camera with a color background (usually green), we will say green in this case. Using special software like Finncast Studio live video streaming software can remove the green background completely and creating a transparent background. With all the green removed Place a new image or other video footage behind the transparent background and this will be the new background. This is very usefully for many purposes like weather reading, use in conjunction with virtual sets, advertisements and even special effects.
There are a number of factors to creating the perfect transparent background even using the best chroma keying software you will need to set the lighting correctly on the green background. Choosing a good quality green screen is also something to consider with no creases. Also popular is special green paint or chroma key paint which is also used in the video industry.
Clothing is also a factor if using a green background and wearing green clothing this will be a problem and the green on the clothing will also become transparent. In cases where green clothing is going to be worn you should use a blue background and vice versa.
The biggest challenge when setting up a green screen or blue screen is even lighting and the avoidance of shadow, because it is best to have as narrow a color range as possible being replaced. A shadow would present itself as a darker color to the camera and might not register for replacement. This can sometimes be seen in low-budget or live broadcasts where the errors cannot be manually repaired. The material being used affects the quality and ease of having it evenly lit. Materials which are shiny will be far less successful than those that are not. A shiny surface will have areas that reflect the lights making them appear pale, while other areas may be darkened. A matte surface will diffuse the reflected light and have a more even color range. In order to get the cleanest key from shooting greenscreen it is necessary to create a value difference between the subject and the greenscreen. In order to differentiate the subject from the screen, a two-stop difference can be used, either by making the greenscreen two stops higher than the subject, or vice versa.
Sometimes a shadow can be used to create a visual effect. Areas of the bluescreen or greenscreen with a shadow on them can be replaced with a darker version of the desired background video image, making it look like the person is casting a shadow on them. Any spill of the chroma key color will make the result look unnatural. A difference in the focal length of the lenses used can affect the success of chroma key.
What to avoid
- Shadows on your green screen do not stand to close to the screen
- Good lighting light the screen well and the subject
- Clothing, do not wear clothing the same color of the screen being used.
- Use a good chroma keying software link Finncast Studio live video streaming software
- If using a material green screen have as little creases in the screen as possible.